tymoczko3e

CHAPTER 14

Digestion: Turning a Meal into Cellular Biochemicals

Page 247

Growing requires vast amounts of energy and biochemical building blocks. These needs do not disappear as we age but are required to maintain our bodies against the wear and tear of living. The energy and building blocks come in the form of food, which must be converted into biochemicals in the process of digestion.

Eating is a basic need of all organisms that relieves hunger and provides energy. For humans, however, eating is far more than consuming fuel. A well-cooked, well-presented meal is a gustatory, olfactory, and visual delight. Indeed, eating is one of the greatest pleasures that we as humans can experience. Sharing a meal, with friends in a playground or heads of state in a grand palace, is a time-honored means of building and strengthening bonds between individuals.

In this chapter, we will take a more prosaic view of eating. We will examine it as the first stage of biochemical fuel generation. Once the food is in our mouth, the process of digestion begins. Digestion is the biochemical set of reactions by which food is converted into molecules that will be further manipulated to yield biologically useful energy and biosynthetic building blocks.